A laser generator employing a solid medium is widely used for cutting machines and small-size equipments such as medical laser scalpels. Titanium-doped sapphire is used as solid medium for a laser generator. However, this material has a short fluorescence lifetime, and it does not generate a laser unless adequate excitation is conducted in a short period of time.
In the case of side excitation by means of e.g. a flash lamp as light source for excitation, it is necessary to excite almost the entire portion of the solid medium. For this purpose, it is necessary to input a large quantity of energy in a short period of time. Further, with a lamp such as a flash lamp, lights with wavelengths incapable of exciting sapphire will simultaneously be generated. Therefore, it has been a problem that the conversion efficiency of energy is low.
As a method for improving such conversion efficiency of energy, it has been common to employ a method wherein a solution tinted with a dye capable of converting light in an ultraviolet region to light in a visible region, is circulated to improve the conversion efficiency of energy. However, this method has the following problems:
1. Deterioration of the dye is unavoidable, and its replacement will be required.
2. It is necessary to always maintain the circulation system of the dye, particularly the light conversion portion, clean so that a high light transmittance be maintained.
3. It is necessary to pay an attention for the safety with respect to e.g. the toxicity of the dye. With these problems, this method can not necessarily be regarded as a suitable method.
The present inventors have conducted various studies for a laser generator free from the above problems. As a result, they have found that when titanium-doped sapphire is employed as laser medium (solid medium), efficient laser generation is possible by disposing a certain solid material in the vicinity of the laser medium and/or in the vicinity of the flash lamp. The present invention has been accomplished on the basis of this discovery.